I am running a new Dell XPS 8930 Desktop running Windows 10. I have a Logitech Z313 Stereo speakers and Subwoofer that worked on my last computer. It has only one line to connect from my computer to the Z313 speaker system.

The back of my desktop has three connections. Front L/R surround line-out port, Rear L/R Surround port and a Center/Subwoofer LFE Surround port. 

Which one should I use for my speakers ? I tried each one to no avail. I have run the Troubleshooter  and every other action that I can think of. Device Manager shows that I am using Realtec Audio and that the Device is working properly.

Can you give me any advice how to fix this?     Thank you for any help you can give me.